A Tiny New Heat Engine With No Moving Parts Just Hit an Incredible Energy Milestone

 

Scientists anticipate that solid-state thermophotovoltaic (TPV) cells with no moving parts would be able to convert heat into energy more efficiently at greater temperatures, paving the path for totally renewable power grids.

 

According to researchers, one of these TPV cells has already achieved a new world record of 40% efficiency. That's better than the steam turbines that have traditionally been used to convert heat to electricity, which have a maximum efficiency of 35 percent and temperature constraints as well.

 

High-energy photons from white-hot heat sources are converted into electricity by TPVs. When used in conjunction with thermal batteries, they might catch solar energy and store it, releasing electricity as needed.

 

"Because they have no moving parts, solid-state energy converters may run at greater temperatures with fewer maintenance costs," says mechanical engineer Asegun Henry of the Massachusetts Institute of Technology (MIT).

 

"They basically sit there and generate electricity reliably."

 

At temperatures ranging from 1,900 to 2,400 degrees Celsius, the thermophotovoltaic cell used in the world-record-breaking conversion can generate electricity from heat sources (3,452 to 4,352 degrees Fahrenheit). Because of the moving parts, those temperatures are far too hot for traditional steam turbines to operate at.

 

These cells' efficiency is now improving, making them more viable. The previous record was 32 percent efficiency, although most TPV cells built to date have had an efficiency rate of around 20%.

 

The efficiency record was achieved by measuring the heat absorbed by the cell, which is around a centimetre squared in size, with a heat flux sensor. The amount of heat that the cell was subjected to was varied using a high-temperature lamp, indicating that it was indeed acceptable for integration into a larger system.

 

"We can get excellent efficiency over a wide range of temperatures that are relevant for thermal batteries," Henry explains.

 

The increased efficiency is mostly owing to the materials utilised, which have a narrow bandgap - the distance that electrons must travel to generate energy. The researchers employed greater bandgap materials and numerous junctions in their study (or material layers).

 

A high bandgap alloy is used to capture high-energy photons and convert them to electricity, a low bandgap alloy is used to capture low-energy photons that slip through the first layer, and a gold mirror is used to reflect photons that have passed all the way through back to the heat source, reducing waste heat.

 

Now that the TPV cell has been demonstrated to be operational, dependable, and efficient, scientists may focus on scaling it up and combining it with other components to create a complete energy production system that produces no carbon while in use.

 

"Thermophotovoltaic cells were the final critical step in proving that thermal batteries are a feasible concept," Henry explains. "This is a significant step on the route to a fully decarbonized grid and the proliferation of renewable energy."

Reference: Journal Nature